The document discusses the concept of price elasticity of demand. It defines price elasticity of demand as the proportionate change in quantity demanded due to a proportionate change in price. It then lists and describes several factors that affect the elasticity of demand, including the nature of the commodity, availability of substitutes, number of uses, proportion of income spent on the good, income level, habits, time period, and consumer expectations about future prices and income. It concludes that knowing whether a good is inferior or normal can help predict consumer behavior changes from price changes and help inform pricing strategies.